Hypocalcemia

Question 1

Hypocalcemia in hungry bone syndrome

Answer 1

seen due after severe hyperparathryoidism (primary or secondary) and preoperative disease

causes low and prolonged post operative hypocalcemia

Question 2

hypocalcemia after parathyroidectomy is

Answer 2

transient and mild (lasting one week) and can occur in pts with normal renal function

Question 3

why does hungry bone syndrome occur?

Answer 3

after being in a state of hyperparathyroidism for so long with increased bone formation and resorption resulting in net efflux of calcium from bones. Acute withdrawal of PTH (surgery) results in imbalance in bone formation and resorption resulting in net influx of calcium into bone.

causes hypocalcemia in serum

Question 4

labs of hungry bone syndrome:

Answer 4

see low calcium, normal or elevated PTH and phosphate and mag will be low (they are absorbed with the calcium so are low)

Question 5

when do we start to see hypocalcemia post parathyroidectomY

Answer 5

2-4 days postoperatively and monitoring of serum calcium levels are 2-4 times a day and oral repletion is recommended.

Question 6

If someone is hypocalcemic with tetany, respiratory distress or serum calcium is <7.5 mg/dl please give

Answer 6

IV calcium

also give magnesium as low levels diminish PTH secretion and develop refractory hypocalcemia.

Question 7

should we replace phosphorus in hungry bone syndrome or with low calcium?

Answer 7

Yes. see serum levels <1mg/dl as it can further exacerbate hypocalcemia.

Question 8

low calcium, high phosphorus and high PTH with CKD

Answer 8

this is due to impaired vitamin D metabolism.

Question 9

what happens with chronic vitamin D deficiency

Answer 9

see osteomalacia, and inaccessible calcium stores in bone (unmineralized osteoid) and eventual hypocalcemia.

They can develop pseudofractures, bone pain and deformity

Question 10

hypocalcemia can be due to

Answer 10

hypoparathyroidism,
poor calcium intake, activating mutations in the calcium sensing receptor of CASR gene
PTH resistance
increased phosphate binding in vascular space (rhabdomyolysis or tumor lysis)
increased citrate chelation in large volume blood transfusions
sepsis
vitamin D deficiency
hypomagnesemia

Question 11

hypomagnesemia causes

Answer 11

functional reversible parathyroid hypofunction which must be excluded before a low or inappropriately normal PTH level is attributed to hypoparathyroidism

Question 12

transient hypocalcemia is commonly after

Answer 12

first 24 hrs after a total thyroidectomy in about 60-90% of pts

Question 13

laryngospasm with inspiratory stridor after thyroidectomy

Answer 13

is a medcial emergency

stridor after thyroidectomy plays a clue to cause

if respiratory distress or stridor is apparent after extubation then there’s bilateral recurrent laryngeal nerve injury

If stridor appears within a few hours of surgery it’s probably a wound hematoma with tracheal compression. Need to remove the bandages and look.

If stridor appears even lader and preceded by paresthesias and muscle cramps then its likely hypoglycemia from transient hypoparathroidism or inadavertent parathyroidectomy

Question 14

pseudohypoparathyroidism is from

Answer 14

autosomal dominant disorder
see shortened forth metacarpal

will have low calcium and so treat with a low dose of calcitriol 0.25 mcg twice daily.

Question 15

albright hereditary osteodystrophy is also known as

Answer 15

pseudohypoparathyroidism
- see PTH insensitivity by organs

see shortened 4th metacarpal,
intellectual disability, obesity and short stature

also see low calcium and hyperphosphatemia